No fenestrated endothelium - induced or invasive - that could exude hematogenous horseradish peroxidase (HRP), has been found in the cerebral tissue adjacent to grafted superior cervical ganglion. The extracellular route taken by blood-borne HRP, from permeable vessels of the graft to brain extracellular fluid, has thus been confirmed. However, the non-fenestrated endothelium of capillaries in the brain adjacent to the graft has many more pits and vesicles than that of neighboring regions; most of them become labeled with HRP coming from the blood itself and the cerebral extracellular clefts. Some of the HRP that escapes from the fenestrated vessels of the graft, enters the subarachnoid space from which it is endocytosed by the bordering astrocytic end-feet adjacent to the graft. The HRP is then transported retrogradely to lysosomes within the astrocyte cell body. The sharply demarcated line of labeled astrocytes stands in sharp contrast to the unlabeled glial cells on either side. Even without HRP, the lysosomes in the same of astrocytes adjacent to the graft, are far more numerous and larger than those of its neighbors, presumably due to the repeated uptake of cellular debris from the ganglion cells that have not found targets and that, consequently, have degenerated.